September 15th 2015

Many things trigger emotions. At a basic level, emotions are full-body, multi-system biological responses to either internal or external stimuli. These responses have helped us survive throughout hundreds of thousands of years of human history; and those same biological processes helped the ancestors from whom we evolved survive as well. Our emotions are affected by incoming sensory input. Among the many sensory stimuli that prompt emotional responses, sound reigns as being prominently involved with our survival. But it's complicated. hearing is more than just hearing. At the mechanical level, our sense of hearing involves mechanotransduction of displaced air by hair cells in the cochlea of the inner ear; essentially, we require the vibrating tactile sensations of sound waves to perceive auditory stimuli. Those sensations give us valuable data about what's happening around us. Are we in danger? Are we safe? Are things changing in our environment that require us to adapt or respond? Sound and our ability to perceive it tells us all of these things.

This recent NPR story which can be heard by clicking on the link captures some of the intricacies of sound, from evolutionary biology to human neurobiology, and its role in the survival and ultimate evolution of our species and others.